Chaos descended on air travellers last week after authorities in the UK revealed allegations that terrorists planned to blow as many as 12 airliners out of the sky. Revelations that the plotters intended to use explosives made from liquids led to bans on liquids and hand luggage. Beefed-up security at airports created long queues, desperate delays and flight cancellations. It also provoked questioning of what more can be done to safeguard aircraft from terrorist attacks.
After 9/11, sharp objects were banned from hand luggage. Shortly afterwards, following Richard Reid鈥檚 thwarted attempt to detonate a shoe bomb, US airports began screening passengers鈥� footwear. For now, different levels of bans exist on liquids. Is this making our flights safer, and where will it all end?
Most airport X-ray scanners will detect bottles, cans and other containers of liquids, but looking for liquids per se is not ideal. Better to spot explosives themselves, or their components, whether in solid or liquid form. A variety of scanners that identify chemicals already exist (see What airports must do to sniff out liquid explosives). Those in use tend to be programmed to spot chemicals commonly found in explosives, such as nitrogen compounds. They can also be tuned to detect substances given off by 鈥渒itchen-chemistry鈥� bombs, like those thought to be at the centre of the suspected UK plot. Explosives experts say the range of chemicals that would need to be detected is not huge, though the rate of false alarms generated and the time taken for screening could cause problems.
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Critics argue that implementing these measures will simply drive terrorists to find new ways to create mayhem. That may be true, but governments can no longer afford to leave this door open. Liquid explosives brought down a Korean Air flight in 1987, killing 115 people, and blew a hole in the floor of a Philippine Airlines flight, killing one person, in 1994. As most airports did not increase surveillance for liquid explosives after those attacks, it left an opportunity for the alleged UK plotters.
Other critics have claimed that bans on hand luggage after 9/11 had no effect, so still stricter security is pointless. Yet in the 18 months from February 2002, screening at US airports intercepted a staggering 54,000 box cutters and 1500 guns. Doubtless these did not all belong to terrorists, but it is hard to argue that flying was not safer without them.
Of course, scanning alone cannot protect aircraft; security relies on a web of overlapping measures. These include increasing the strength of flight deck doors and carrying air marshals on flights, employing sniffer dogs, making sure would-be terrorists are not employed at airports, and restricting access to explosives. Then there is intelligence 鈥� monitoring people rather than 鈥渢hings鈥� 鈥� which is credited with exposing the alleged UK plot. This type of prevention must be better than clearing up after a disaster. It is, however, far from foolproof, as some lamentable failures by British police and intelligence services have shown in the past two years.
One other form of intelligence has raised its head this week: the idea of profiling people at airports. Israel has used the appearance and behaviour of travellers to identify people for more thorough searches and interrogation. In the US and UK, proposals for such a policy have been roundly criticised on human rights grounds, not least because in the present climate those singled out are likely to be young men of Asian or Arab appearance.
Screening technology is just one line of defence in the web of measures that safeguard aircraft. Like all the others it is fallible, but the hope is that the web as a whole will deter anyone from even trying to smuggle explosives on board. Sadly, terrorists will always be likely to target aircraft: flying is the one mode of transport where a small explosion can create spectacular devastation with huge economic and psychological impact (see Stop television unravelling your reality). Beyond the airport fence, governments are already discussing how to protect airliners from attack by shoulder-launched missiles.
鈥淪creening is just one line of defence in the web of measures that safeguard aircraft. Like all the others it is fallible鈥�
Peter Zimmerman, professor of science and society at King鈥檚 College London, likens aircraft security to a seriously biased game of chess. Checkmate is just a few clever moves away for the opposition, but the authorities can only ever force a draw. By that analogy, we need every piece on the board, every tactic and plenty of smart thinking to stay in the game.
